CA1069170A - Drive circuits for direct current electric motors - Google Patents
Drive circuits for direct current electric motorsInfo
- Publication number
- CA1069170A CA1069170A CA264,734A CA264734A CA1069170A CA 1069170 A CA1069170 A CA 1069170A CA 264734 A CA264734 A CA 264734A CA 1069170 A CA1069170 A CA 1069170A
- Authority
- CA
- Canada
- Prior art keywords
- field windings
- motor
- circuit according
- controlled rectifiers
- direct current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000004804 winding Methods 0.000 claims abstract description 36
- 230000000295 complement effect Effects 0.000 claims abstract description 7
- 239000003990 capacitor Substances 0.000 claims abstract description 6
- 230000000903 blocking effect Effects 0.000 claims description 6
- 230000008878 coupling Effects 0.000 claims description 2
- 238000010168 coupling process Methods 0.000 claims description 2
- 238000005859 coupling reaction Methods 0.000 claims description 2
- 229940035564 duration Drugs 0.000 claims 1
- 238000010276 construction Methods 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
- H02P1/16—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters
- H02P1/18—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual DC motor
- H02P1/22—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual DC motor in either direction of rotation
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P7/00—Arrangements for regulating or controlling the speed or torque of electric DC motors
- H02P7/06—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current
- H02P7/18—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power
- H02P7/24—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices
- H02P7/28—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices
- H02P7/282—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling field supply only
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Motors That Do Not Use Commutators (AREA)
- Control Of Direct Current Motors (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A circuit comprising a direct current motor having two parallel oppositely wound field windings, a pair of controlled rectifiers, each connected in series with a respective one of the said field windings. A commutating capacitor couples the controlled rectifiers, and an astable multivibrator are provided for applying gating signals to the two controlled rectifiers alternately for causing con-duction of direct current through the two field windings in alternate complementary conduction periods.
A circuit comprising a direct current motor having two parallel oppositely wound field windings, a pair of controlled rectifiers, each connected in series with a respective one of the said field windings. A commutating capacitor couples the controlled rectifiers, and an astable multivibrator are provided for applying gating signals to the two controlled rectifiers alternately for causing con-duction of direct current through the two field windings in alternate complementary conduction periods.
Description
'' ` 10~ 0 This invention relates to drive circuits for direct current electric motors.
According to the invention, a drive circuit comprises a direct current motor having two parallel oppositely wound field windings, a pair of controlled rectifiers, each connected in series with a respective one of the said field windings, a commutating capacitor coupling the controlled rectifiersl and means for applying gating signals to the two controlled rectifiers alternately for causing conduction of direct current through the two field windings ~o in alternate complementary conduction periods.
In such a circuit each of the aforementioned controlled rectifiers (which are preferably thyristors) acts as a main current switch for the winding with which it is in series and an exting-uishing switch for the other controlled rectifier. The periods of conduction of one controlled rectifier are complementary to those of the other. If the periods of conduction are e~ual, ~ the opposed field windings are energised alternately with substant-: ially equal pulses of curre-nt so that, provided that the frequency of commutation is high er,ough, the motor is at a standstill.
Equalisation of the conduction periods occurs when the successive intervals between the gating signals applied to the rectifiers alternately are equaL for instance when the gating signals are rectangular waveforms of unity mark-to-space ratio but in antiphase.
; The two fiald windings constitute a transformer, the action of , 25 which keeps the currents through the windings very low at stand-; still. The transformer also inhibits the appearance of over-voltages across the controlled rectifiers. Variation of the relative timing of the gating signals will alter the average -~
currents flowing through the field windings differentially so that the motor will be driven in one or other direction according to which winding reçei~-es the greater average current.
Because tne starting, stopping and reve~sing of the ' ' ~-0~91~0 ..
motor can be effected merely by adjusting the relative timing of the gating signals, the use of contactors for these operations can readily be avoided. -In order ~o permit the appliction of reverse voltages to the thyristors and to limit the discharge current of the com-mutating capacitor, a choke may conjointly couple the cathodes of the controlled rectifiers to the appropriate terminal of the ;~ source of power. However, the armature of the motor, in the case of a series wound motor, may perform the same functions ' 10 as the choke and therefore the armature of the motor may couple ~:; the cathodes of the controlled rectifiers to a terminal of the source of power.
There follows a description of two embodiments of the invention by way of example, reference being made hereinafter to the accompanying drawings, of which Figures 1 and 2 each show - in simplified form a drive circuit for a direct current electric ~` motor.
i,~.
The circuit shown in Figure 1 includes a positive terminal 1 and a negative terminal 2. These terminals would normally be connected to the appropriate terminals of an electric storage battery. I'he motor has two parallel field windings 3 an~ 4 which are disposed to produce, when energised normally with current , from the batter~, electric fluxes in opposite directions. In ;, this embodiment the motor is a series motor, of which the armature 5 is connected between the terminal 1 and the field windings ' 3 and 4.
! A Eree wheeling diode 6 is disposed, in accordance ; with ordinary practice, across the armature 5 of the motor.
l~ The commutating network for the motor basically comprises ;i~ 30 two con'~rolled rectiflers, in this embodiment the thyristors ~; 7 and 8. Each thyristor is in series with a respective one of ;~ ~ the field windings 3 and 4. The anodes of the thyristors are ,.......... . .
- -` 1069170 connected by a commutating capacitor 9O In this network each :: thyristor acts as a main thyristor for the passage of current j. through the respective field winding and.also, when rendered :
conductive, as an extinguishing thyristor for the main thyristor of the other winding.
The circuit shown in Figure 1 also includes a blocking diode 10 interposed between the field winding 3 and the thyristor -:; 7 and a blocking diode 11 interposed between the field winding - 4 and the thyristor 8. A free wheeling diode 12 is connected :~ 10 between the negative terminal 2 and to a point on the circuit - path between the field winding 3 and the blocking diode 10.
A free wheeling diode 13 is connected between the terminal 2 :
and a point on the circuit path betw~en the field winding 4 and the blocking diode 11. The cathodes of the thyristors are connec~ed .~ 15 together and conjointly through a choke 14 to the negative terminal : . .
~ The gates of thristors 7 and 8 are connected to output f "~ ` . .
terminals of an astable multivibrator 15, which produces at its . output terrllinals two complementary rectangular wave switching ,` 20 wave forms of which the mark-to-space ratio is variable i.n a co~..plementary manner. The particular construction of the astabl-multivibrator is not important. The operating frequency of the : ., .
astable multivibrator is likewise not important provided tha~, :
when the mark-to-space ratios of its complementary outputs are 25 equal, so that the periods of conduction of the thyristors 7 .
and 8, and the periods of current flow in the respective windings .. . .
are likewise equal, the motor is stationary. Motion of the motor in one or other direction can be produced by varying the mark-to-space ratio of one of the outputs of the multivibrator, and ~0 correspondingly varying the mark-to-space ratio of the other output in a comp.lentary manner so that the periods of conduction as aforesaid alter differentially so as to increase the average :: :
'; : '.' ' ' . .
. . . .
```- 1069170 .
current flowing through one of the field windings at the expense of the average current flowing through the other.
The circuit shown in Figure 2 differs from the circuit shown in Figure 1 by the ommissiion of the choke 14 and the re- -placement of the armature of the motor in the position occupied ' by the choke. In this embodiment the free wheeling diode 6 is unnecessary and is omitted.
It would be possible to reduce the currents flowing through the windings when the motor is at a standstill more by the incorporation of the windings of a transformer (not shown) in series with the field windings.
, .
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According to the invention, a drive circuit comprises a direct current motor having two parallel oppositely wound field windings, a pair of controlled rectifiers, each connected in series with a respective one of the said field windings, a commutating capacitor coupling the controlled rectifiersl and means for applying gating signals to the two controlled rectifiers alternately for causing conduction of direct current through the two field windings ~o in alternate complementary conduction periods.
In such a circuit each of the aforementioned controlled rectifiers (which are preferably thyristors) acts as a main current switch for the winding with which it is in series and an exting-uishing switch for the other controlled rectifier. The periods of conduction of one controlled rectifier are complementary to those of the other. If the periods of conduction are e~ual, ~ the opposed field windings are energised alternately with substant-: ially equal pulses of curre-nt so that, provided that the frequency of commutation is high er,ough, the motor is at a standstill.
Equalisation of the conduction periods occurs when the successive intervals between the gating signals applied to the rectifiers alternately are equaL for instance when the gating signals are rectangular waveforms of unity mark-to-space ratio but in antiphase.
; The two fiald windings constitute a transformer, the action of , 25 which keeps the currents through the windings very low at stand-; still. The transformer also inhibits the appearance of over-voltages across the controlled rectifiers. Variation of the relative timing of the gating signals will alter the average -~
currents flowing through the field windings differentially so that the motor will be driven in one or other direction according to which winding reçei~-es the greater average current.
Because tne starting, stopping and reve~sing of the ' ' ~-0~91~0 ..
motor can be effected merely by adjusting the relative timing of the gating signals, the use of contactors for these operations can readily be avoided. -In order ~o permit the appliction of reverse voltages to the thyristors and to limit the discharge current of the com-mutating capacitor, a choke may conjointly couple the cathodes of the controlled rectifiers to the appropriate terminal of the ;~ source of power. However, the armature of the motor, in the case of a series wound motor, may perform the same functions ' 10 as the choke and therefore the armature of the motor may couple ~:; the cathodes of the controlled rectifiers to a terminal of the source of power.
There follows a description of two embodiments of the invention by way of example, reference being made hereinafter to the accompanying drawings, of which Figures 1 and 2 each show - in simplified form a drive circuit for a direct current electric ~` motor.
i,~.
The circuit shown in Figure 1 includes a positive terminal 1 and a negative terminal 2. These terminals would normally be connected to the appropriate terminals of an electric storage battery. I'he motor has two parallel field windings 3 an~ 4 which are disposed to produce, when energised normally with current , from the batter~, electric fluxes in opposite directions. In ;, this embodiment the motor is a series motor, of which the armature 5 is connected between the terminal 1 and the field windings ' 3 and 4.
! A Eree wheeling diode 6 is disposed, in accordance ; with ordinary practice, across the armature 5 of the motor.
l~ The commutating network for the motor basically comprises ;i~ 30 two con'~rolled rectiflers, in this embodiment the thyristors ~; 7 and 8. Each thyristor is in series with a respective one of ;~ ~ the field windings 3 and 4. The anodes of the thyristors are ,.......... . .
- -` 1069170 connected by a commutating capacitor 9O In this network each :: thyristor acts as a main thyristor for the passage of current j. through the respective field winding and.also, when rendered :
conductive, as an extinguishing thyristor for the main thyristor of the other winding.
The circuit shown in Figure 1 also includes a blocking diode 10 interposed between the field winding 3 and the thyristor -:; 7 and a blocking diode 11 interposed between the field winding - 4 and the thyristor 8. A free wheeling diode 12 is connected :~ 10 between the negative terminal 2 and to a point on the circuit - path between the field winding 3 and the blocking diode 10.
A free wheeling diode 13 is connected between the terminal 2 :
and a point on the circuit path betw~en the field winding 4 and the blocking diode 11. The cathodes of the thyristors are connec~ed .~ 15 together and conjointly through a choke 14 to the negative terminal : . .
~ The gates of thristors 7 and 8 are connected to output f "~ ` . .
terminals of an astable multivibrator 15, which produces at its . output terrllinals two complementary rectangular wave switching ,` 20 wave forms of which the mark-to-space ratio is variable i.n a co~..plementary manner. The particular construction of the astabl-multivibrator is not important. The operating frequency of the : ., .
astable multivibrator is likewise not important provided tha~, :
when the mark-to-space ratios of its complementary outputs are 25 equal, so that the periods of conduction of the thyristors 7 .
and 8, and the periods of current flow in the respective windings .. . .
are likewise equal, the motor is stationary. Motion of the motor in one or other direction can be produced by varying the mark-to-space ratio of one of the outputs of the multivibrator, and ~0 correspondingly varying the mark-to-space ratio of the other output in a comp.lentary manner so that the periods of conduction as aforesaid alter differentially so as to increase the average :: :
'; : '.' ' ' . .
. . . .
```- 1069170 .
current flowing through one of the field windings at the expense of the average current flowing through the other.
The circuit shown in Figure 2 differs from the circuit shown in Figure 1 by the ommissiion of the choke 14 and the re- -placement of the armature of the motor in the position occupied ' by the choke. In this embodiment the free wheeling diode 6 is unnecessary and is omitted.
It would be possible to reduce the currents flowing through the windings when the motor is at a standstill more by the incorporation of the windings of a transformer (not shown) in series with the field windings.
, .
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';'~ ' :
.,~ .
'"', " ~
:i. ' :~,''`' ` .
~; .
~,....
" ' . ,~
: .
. `~ , .
. .
Claims (10)
1. A circuit comprising a direct current motor having two parallel oppositely wound field windings, a pair of controlled rectifiers, each connected in series with a respective one of the said field windings, a commutating capacitor coupling the controlled rectifiers, and a signal generator for applying gating-signals to the two controlled rectifiers from respective outputs of said signal generator alternately for causing conduction of direct current through the two field windings in alternate comple-mentary conduction periods, said signal generator being control-lable to vary the relative duration of said conduction periods, and the frequency of the gating signals being such that when the alternate complementary conduction periods are of equal dur-ation, the motor is stationary.
2. A circuit according to claim 1 wherein said field windings and controlled rectifiers are arranged to conduct dir-ect current flowing from one to the other of a pair of supply terminals.
3. A circuit according to claim 2 wherein a choke coil conjointly couples the cathodes of the controllable rectifiers to the said other supply terminal.
4. A circuit according to claim 2 wherein the motor is a series wound motor having an armature which conjointly couples the cathodes of the controllable rectifiers to the said other supply terminal.
5. A circuit according to claim 2 wherein the motor is a series wound motor having an armature coupled between the said
5. A circuit according to claim 2 wherein the motor is a series wound motor having an armature coupled between the said
Claim 5 continued....
one supply terminal and a common connection between said parallel field windings.
one supply terminal and a common connection between said parallel field windings.
6. A circuit according to claim 5 wherein a freewheeling diode is connected across the armature of the motor.
7. A circuit according to claim 1 wherein the commutating capacitor is connected between the anodes of the controlled rectifiers, and wherein there is provided a pair of blocking diodes, each connected between a respective one of the field windings and the associated controlled rectifier.
8. A circuit according to claim 7 including a pair of freewheeling diodes each connected between the said other supply terminal and a point between a respective one of the field windings and the associated blocking diode.
9. A circuit according to claim 1 wherein the signal generator comprises an astable multivibrator.
10. A circuit according to claim 1 including a transformer having windings in series with the field windings for reducing the currents flowing through said field windings when the motor is at a standstill.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB45785/75A GB1532797A (en) | 1975-11-04 | 1975-11-04 | Drive circuits for direct current electric motors |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1069170A true CA1069170A (en) | 1980-01-01 |
Family
ID=10438598
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA264,734A Expired CA1069170A (en) | 1975-11-04 | 1976-11-02 | Drive circuits for direct current electric motors |
Country Status (8)
| Country | Link |
|---|---|
| AU (1) | AU504542B2 (en) |
| CA (1) | CA1069170A (en) |
| CH (1) | CH600672A5 (en) |
| DE (1) | DE2650409A1 (en) |
| FR (1) | FR2331194A1 (en) |
| GB (1) | GB1532797A (en) |
| NL (1) | NL7612131A (en) |
| SE (1) | SE7612244L (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2839712C3 (en) * | 1978-09-13 | 1981-07-09 | Danfoss A/S, 6430 Nordborg | Circuit with chopper function for a brushless DC motor |
| US4385266A (en) * | 1980-03-18 | 1983-05-24 | Technical Operations Limited | Field weakening system for pulse-controlled three-terminal d.c. motor |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3302089A (en) * | 1964-02-07 | 1967-01-31 | Westinghouse Electric Corp | System for controlling the output of plural field dynamoelectric machine |
| US3727118A (en) * | 1969-12-10 | 1973-04-10 | Nippon Yusoki Co Ltd | Contactless reversible device in an electric car |
-
1975
- 1975-11-04 GB GB45785/75A patent/GB1532797A/en not_active Expired
-
1976
- 1976-11-02 CA CA264,734A patent/CA1069170A/en not_active Expired
- 1976-11-02 AU AU19264/76A patent/AU504542B2/en not_active Expired
- 1976-11-02 NL NL7612131A patent/NL7612131A/en not_active Application Discontinuation
- 1976-11-03 DE DE19762650409 patent/DE2650409A1/en not_active Withdrawn
- 1976-11-03 CH CH1388276A patent/CH600672A5/xx not_active IP Right Cessation
- 1976-11-03 SE SE7612244A patent/SE7612244L/en unknown
- 1976-11-04 FR FR7633262A patent/FR2331194A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| AU504542B2 (en) | 1979-10-18 |
| AU1926476A (en) | 1978-05-11 |
| FR2331194A1 (en) | 1977-06-03 |
| DE2650409A1 (en) | 1977-05-05 |
| GB1532797A (en) | 1978-11-22 |
| SE7612244L (en) | 1977-05-05 |
| CH600672A5 (en) | 1978-06-30 |
| NL7612131A (en) | 1977-05-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |